You should know what you paid over $1000 for, at least the display size and there is no reason to be rude. We get posters here all the time that say they got a new 27" iMac when it really turns out they got a "new to them" used 27" iMac which what I thought you had as you did not tell us the scanner you own and did not correctly identify your iMac.
To check to see if your scanner works with the version of Mac OS installed on the computer please go to the Scanner Mfg's web site and see if they support the version of Mac OS installed. If they do, update with their drivers.
If they no longer support it then go to Hamrick.com and download the free evaluation version of VueScan and see if your scanner is supported, there is a good chance it is. If it works, their software is reasonably priced.